Winds, Storm and Cyclones
Science Class Seven
Thunderstorms & Cyclones
Thunderstorms
The strong wind accompanied by lightning is called Thunderstorm. Thunderstorm is known as electrical storm or lightning storm also.
Thunderstorm develops in hot, humid, and tropical zones.
How does a Thunderstorm form?
After receiving more heat, the air in the hot and humid area becomes light and rises up quickly. The water droplets also rise up along with the air. After reaching a particular height, water droplets freeze and start falling down. This swift movement of falling water droplets and rising hot air together create the lightning effect.
This phenomenon continues and thunderstorm forms.
We can hear the thunder sound and see the lightning effect while in a thunderstorm.
The speed of light is more than that of sound. This is the cause that we see lightning before the thunder sound.
Safety during a thunderstorm
Lightning is very dangerous; this may lead to severe damage to life even. So, it is necessary to take safety measures during a thunderstorm.
Some safety measures during a thunderstorm.
(1) Try to stay indoor/home
(2) Do not take shelter near an isolated tree
(3) Do not stand near water bodies
(4) Do not stand near a pole
(5) Do not stay near an elevated area, like mountains, hills, etc.
(6) Do not stand near objects that conduct electricity
(7) If in open, do not lay on the ground
(8) Do not take shelter under an umbrella
(9) If you are in the water, get out and try to go indoors.
Cyclone
Cyclones are similar to whirlpools in the air. To balance the huge pressure difference, air rushes towards the area of the low-pressure zone. The flow of high speed wind creates airflow in a circular motion. The circular motion of air movement creates a cyclone.
This happens when the air over a very large area rises up because of heating. This results in wind movement from top to bottom in the center and from bottom to top in the periphery of a cyclone.
The center of the cyclone is called the 'eye'. The movement of cyclones is in the anti-clockwise direction in the northern hemisphere and in the clockwise direction in the southern hemisphere.
Factors that form cyclones
The formation of cyclones and thunderstorms depends on many factors. The main factors are wind speed, wind direction temperature, and humidity.
How a thunderstorm becomes a cyclone?
Water start evaporating after receiving heat. The accumulation of water vapour forms clouds. When the cloud rises up, it gets condensed and changes into liquid and starts falling down in the form of raindrops.
During the condensation of water vapour, which is in the process of changing clouds in the liquid, the heat is released into the atmosphere. This heat warms the air around. After getting heat air in the atmosphere starts rising up creating a zone of low pressure. To fulfill this low pressure zone, more air rushes towards it, which is the center of the storm.
The chain of this process continues and a very low pressure zone is formed in the center of the storm. This resulted in the very high speed winds revolving around it.
Formation of this situation is called a cyclone.
The diameter of a cyclone can be small to very large. It may be up to many kilometers big. This means the diameter of a cyclone can be up to or more than 150 km.
The center of a cyclone is called "the eye of the cyclone". The eye can vary from 10 to 30 km or even bigger.
The center of a cyclone is a region free of clouds and has light winds. Around the eye which is a comparatively calm area, there is a cloud region. The speed of wind in the cloud region of a cyclone may be up to 250 km per hour or even more.
Destruction because of a cyclone
A thunderstorm is dangerous but a cyclone can be devastating.
Because of the high pressure of high speed wind of a cyclone, seawater is pushed towards the shore. This inundates thousands of houses.
High speed winds of a cyclone uproot many trees and poles causing tremendous loss of life and properties.
The heavy rainfall during a cyclone worsens the situation further.
Other names of Cyclone
A cyclone is known by different names in different parts of the world. It is called a 'hurricane' in the American continent. In the Philippines and Japan, it is called 'typhoon'.
Tornadoes
Tornadoes are very similar to a cyclone. A tornado is a dark funnel shaped cloud that reaches from the sky to the ground. Although most tornadoes are weak, but some tornadoes can travel at speeds of about 300 km per hour or even more. A tornado may form within a cyclone. Although, tornadoes are not frequent in the country like India, but they may also be very dangerous and disastrous.
Safety measures during a cyclone:
Government agencies work for safety measures. The government does the following thing to keep the people safe from cyclones and other disasters.
Department of meteorology does forecast about the cyclone. The name of this Government agency is 'Cyclone Forecast and Warning Service'. This agency sends Rapid communication of warnings to the followings:
• The Government agencies
• The ports
• Fishermen
• Ships and
• The general public.
Government makes cyclone shelters in the cyclone prone areas, and other administrative arrangements for moving people fast to safer places.
Action on the part of the people
People who live the cyclone prone areas should take the following preventive measures:
• They should pay attention to the warnings issued from time to time by the Department of Meteorology through TV, radio, and newspapers. They should not ignore those warnings.
• They should always have ready made necessary arrangements. Such as shifting essential household goods, domestic animals, vehicles, etc. to safer places.
• In the condition of a cyclone always avoid driving on roads through standing water, as floods may have damaged the roads.
• Always keep ready the phone numbers of all emergency services, such as police, fire brigade, and medical centers.
• Always store drinking water for emergencies. Other water may be contaminated.
• Never touch wet switches and fallen power lines.
• Do not go out just for the sake of fun.
• Do not pressurise the rescue force by making undue demands.
• Always cooperate and help your neighbours and friends.
Advanced Technology has Helped
In the era of modern technology, we are better protected from these natural disasters. Now a day's warnings are given much before the hitting of cyclones. This becomes possible because of many new technologies. We should thank the satellites and radars which made this possible. Usually, alerts for cyclones are issued 48 hours in advance and people have sufficient time to take preventive measures. Radio, TV, and the internet help these a lot to communicate the warning in faster way.
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